This invention relates to a furnace construction having a suspended, readily expandable floor structure capable of withstanding temperatures in excess of 3500.degree. F. and, more particularly, to such a furnace structure having a unique method of sealing its furnace chamber and a novel method of loading and unloading the furnace with a refractory material.
Heretofore, a substantial difficulty has been experienced in building and maintaining furnaces wherein the operating temperatures exceeded 3500.degree. F. principally because of the scarcity of insulating materials that will withstand these temperatures. In practical terms, the choice of materials has come down to two principal materials, namely, carbon in the form of graphite carbon block or carbon black, and magnesium oxide (MgO). Unfortunately, magnesium oxide readily fluxes and vaporizes at temperatures of these magnitudes in the presence of SiO.sub.2 and most other oxides and contaminates the ingots produced in these furnaces. Therefore, it is desirable to be able to construct a furnace for making refractory ingots which will not use magnesium oxide to obtain its structural integrity and insulating capability.
A second major problem in operating furnaces at such high temperatures is that of controlling the expansion of the internal members which define the furnace chamber so that they will not fail due to thermal expansion mismatch or binding during thermal expansion.
Difficulties in sealing the furnace chamber and in loading and unloading furnaces at such high operating temperatures also exist which, of course, directly affect the thermal efficiency and thereby the cost of operating such furnaces.